The present application relates to architectural tools, and more particularly tools for estimating the position and dimensions of shadows.
The addition of shadows to a complex model can greatly enhance the understanding of that model""s geometry. The human visual system uses shadows as a cue for depth and shape. Consequently, shadows are very useful for conveying the three dimensional nature of objects and for adding realism to complex models. Additionally, many jurisdictions take into consideration the shadows that will be cast by proposed structures in order to grant building permits. Thus, it is often imperative that an applicant for a building permit be able to provide thorough and accurate estimates of the shadows that will be cast.
Current methods for estimating the shadow cast by a structure use a series of graphs for estimating the solar shadow. These methods include the use of horizontal and vertical shadow mast diagrams, which are commonly produced for variables including Apparent Solar Time (AST), the declination angle of the sun with respect to the center of the earth (d), solar azimuth angle, A (A=0 degrees for north, 90 degrees for east, etc.), northern geographical latitude (L), and solar altitude angle (h). These methods include horizontal shadow mast diagrams in which the latitude, L, is fixed for the shadow mast cast on a horizontal plane at various d, A, h, and AST. Alternatively, the method may include horizontal shadow mast diagrams for fixed L and d, for varying A, h, and AST. The methods also include vertical shadow mast diagrams in which L and A are fixed for the shadow of the mast to be cast on a vertical plane for varying h, d, and AST.
These methods tend to be extremely tedious and time consuming for implementation. Problems encountered by many architects include excessive number of projection lines on the graphs which are likely to cause confusion. Furthermore, an inherent defect with these methods is that the shadow for the mast during sunrise and sunset (when the h is low) cannot be shown on the diagrams.
Another commonly used method is to read off altitude angle, h for the concerned AST and A (or AST and d) from solar charts. The altitude angle, h is then manipulated graphically, and the shadow cast by direct sunlight is estimated by trigonometric calculations. This process involves conversion of altitude angle, h from an angle to a ratio of numerals by trigonometric relationships for shadow calculation and subsequent plotting on the drawing paper with rulers and angle protractors. The foregoing results in the marking of shadow points and additional projection lines on the drawing paper which become confusing.
Accordingly, it would be advantageous if the process for estimating the shadow cast by a structure or its features could be less time consuming and tedious. It would also be advantageous if the models estimating the shadow cast by a structure or its features could be simplified.
Disclosed herein is an apparatus for estimating a shadow. The apparatus includes a circular disk and declination lines associated with particular dates of the year. The declination lines are parallel to a diameter of the circular disk and correspond to the declination angle of the earth on the date associated therewith. The apparatus also includes arcs which correspond to particular times of day. The circular disk can also include a slot traversing a second diameter which facilitates insertion of a pencil tip therein.